1. Field of the Invention
The present invention relates to a radiation phase image radiographing apparatus using a Talbot interferometer.
2. Description of the Related Art
The use of a Talbot interferometer, which produces Talbot effect by a diffraction grating and generates Moire fringes in combination with another diffraction grating, to X-ray applications has been studied as described, for example, in U.S. Pat. No. 5,812,629 (Patent Document 1) and U.S. Pat. No. 7,180,979 (Patent Document 2).
For example, Patent Document 2 proposes an X-ray imaging apparatus using a Talbot interferometer that includes an X-ray source, two diffraction gratings, and an X-ray image detector.
In the X-ray imaging apparatus described in Patent Document 2, both the two diffraction gratings and X-ray image detector are formed on a planar substrate. Where parallel beam, such as synchrotron radiation is used, the planar shape described above does not pose any problems, but it gives rise to a problem in medical diagnostic applications and the like in which an X-ray source that radiates widely spreading beams is generally used. That is, X-rays pass through the diffraction gratings at a center portion without any difficulty, but at a portion other than the center portion, X-rays are blocked by diffraction members and unable to pass through the diffraction gratings because the X-rays are incident from oblique directions. For example, Japanese Unexamined Patent Publication No. 2006-259264 (Patent Document 3) proposes an amplitude diffraction grating in which metal X-ray absorption members, each having a width of 2 to 10 μm and a thickness of 25 to 100 μm, are disposed at an equal interval of 2 to 10 μm. It can be thought that the use of such a diffraction grating may possibly cause the problem described above. Accordingly, large-size X-ray phase imaging has been difficult in medical diagnostic applications.
In view of the circumstances described above, it is an object of the present invention to provide a radiation phase image radiographing apparatus capable of performing large-size radiation phase imaging.